A compound isolated from a cyanobacterium, a type of blue-green algae known as Nostoc, shows promise of becoming a natural drug candidate for fighting Alzheimer's and other neurodegenerative diseases, according to an in vitro study by researchers in Switzerland. It is believed to be the first time that a potent agent against Alzheimer's has been isolated from cyanobacteria, commonly known as 'pond scum.' The study was published in the Dec. 26 issue of the Journal of Natural Products, a monthly peer-reviewed joint publication of the American Chemical Society and the American Society of Pharmacognosy.

Cyanobacteria and other marine natural products have been increasingly found to be a promising source of drug candidates for fighting a variety of human diseases, including cancer and bacterial infections, but their chemistry has been largely unexplored, experts say. Now, a common marine organism could lead to yet another potential health benefit, says study leader Karl Gademann, Ph.D., an organic chemist at the Swiss Federal Institute of Technology (ETH) in ZÃ¼rich. Gademann's lab specializes in identifying, synthesizing and studying new bioactive compounds from natural sources.

There is no cure for Alzheimer's at present, although cholinesterase inhibitors have shown promise for delaying or preventing the symptoms of mild to moderate forms of the disease, experts say. The newly isolated compound, nostocarboline, was shown to be a potent inhibitor of cholinesterase -- a brain chemical thought to be important for memory and thinking -- whose breakdown has been associated with the disease's progression. The natural compound's potency is comparable to galanthamine, a cholinesterase inhibitor already approved for the treatment of Alzheimer's, the researchers say.